1 /* SPDX-License-Identifier: GPL-2.0+ */ 2 /* 3 * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition. 4 * 5 * Copyright IBM Corporation, 2008 6 * 7 * Author: Paul E. McKenney <paulmck@linux.ibm.com> 8 * 9 * For detailed explanation of Read-Copy Update mechanism see - 10 * Documentation/RCU 11 */ 12 #ifndef __LINUX_TINY_H 13 #define __LINUX_TINY_H 14 15 #include <asm/param.h> /* for HZ */ 16 17 struct rcu_gp_oldstate { 18 unsigned long rgos_norm; 19 }; 20 21 // Maximum number of rcu_gp_oldstate values corresponding to 22 // not-yet-completed RCU grace periods. 23 #define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 2 24 25 /* 26 * Are the two oldstate values the same? See the Tree RCU version for 27 * docbook header. 28 */ 29 static inline bool same_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp1, 30 struct rcu_gp_oldstate *rgosp2) 31 { 32 return rgosp1->rgos_norm == rgosp2->rgos_norm; 33 } 34 35 unsigned long get_state_synchronize_rcu(void); 36 37 static inline void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 38 { 39 rgosp->rgos_norm = get_state_synchronize_rcu(); 40 } 41 42 unsigned long start_poll_synchronize_rcu(void); 43 44 static inline void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 45 { 46 rgosp->rgos_norm = start_poll_synchronize_rcu(); 47 } 48 49 bool poll_state_synchronize_rcu(unsigned long oldstate); 50 51 static inline bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 52 { 53 return poll_state_synchronize_rcu(rgosp->rgos_norm); 54 } 55 56 static inline void cond_synchronize_rcu(unsigned long oldstate) 57 { 58 might_sleep(); 59 } 60 61 static inline void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp) 62 { 63 cond_synchronize_rcu(rgosp->rgos_norm); 64 } 65 66 static inline unsigned long start_poll_synchronize_rcu_expedited(void) 67 { 68 return start_poll_synchronize_rcu(); 69 } 70 71 static inline void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp) 72 { 73 rgosp->rgos_norm = start_poll_synchronize_rcu_expedited(); 74 } 75 76 static inline void cond_synchronize_rcu_expedited(unsigned long oldstate) 77 { 78 cond_synchronize_rcu(oldstate); 79 } 80 81 static inline void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp) 82 { 83 cond_synchronize_rcu_expedited(rgosp->rgos_norm); 84 } 85 86 extern void rcu_barrier(void); 87 88 static inline void synchronize_rcu_expedited(void) 89 { 90 synchronize_rcu(); 91 } 92 93 /* 94 * Add one more declaration of kvfree() here. It is 95 * not so straight forward to just include <linux/mm.h> 96 * where it is defined due to getting many compile 97 * errors caused by that include. 98 */ 99 extern void kvfree(const void *addr); 100 101 static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) 102 { 103 if (head) { 104 call_rcu(head, func); 105 return; 106 } 107 108 // kvfree_rcu(one_arg) call. 109 might_sleep(); 110 synchronize_rcu(); 111 kvfree((void *) func); 112 } 113 114 #ifdef CONFIG_KASAN_GENERIC 115 void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func); 116 #else 117 static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) 118 { 119 __kvfree_call_rcu(head, func); 120 } 121 #endif 122 123 void rcu_qs(void); 124 125 static inline void rcu_softirq_qs(void) 126 { 127 rcu_qs(); 128 } 129 130 #define rcu_note_context_switch(preempt) \ 131 do { \ 132 rcu_qs(); \ 133 rcu_tasks_qs(current, (preempt)); \ 134 } while (0) 135 136 static inline int rcu_needs_cpu(void) 137 { 138 return 0; 139 } 140 141 /* 142 * Take advantage of the fact that there is only one CPU, which 143 * allows us to ignore virtualization-based context switches. 144 */ 145 static inline void rcu_virt_note_context_switch(int cpu) { } 146 static inline void rcu_cpu_stall_reset(void) { } 147 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } 148 static inline void rcu_irq_exit_check_preempt(void) { } 149 #define rcu_is_idle_cpu(cpu) \ 150 (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq()) 151 static inline void exit_rcu(void) { } 152 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) 153 { 154 return false; 155 } 156 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { } 157 #ifdef CONFIG_SRCU 158 void rcu_scheduler_starting(void); 159 #else /* #ifndef CONFIG_SRCU */ 160 static inline void rcu_scheduler_starting(void) { } 161 #endif /* #else #ifndef CONFIG_SRCU */ 162 static inline void rcu_end_inkernel_boot(void) { } 163 static inline bool rcu_inkernel_boot_has_ended(void) { return true; } 164 static inline bool rcu_is_watching(void) { return true; } 165 static inline void rcu_momentary_dyntick_idle(void) { } 166 static inline void kfree_rcu_scheduler_running(void) { } 167 static inline bool rcu_gp_might_be_stalled(void) { return false; } 168 169 /* Avoid RCU read-side critical sections leaking across. */ 170 static inline void rcu_all_qs(void) { barrier(); } 171 172 /* RCUtree hotplug events */ 173 #define rcutree_prepare_cpu NULL 174 #define rcutree_online_cpu NULL 175 #define rcutree_offline_cpu NULL 176 #define rcutree_dead_cpu NULL 177 #define rcutree_dying_cpu NULL 178 static inline void rcu_cpu_starting(unsigned int cpu) { } 179 180 #endif /* __LINUX_RCUTINY_H */ 181